iPhone and GPS

The iPhone has pseudo-GPS, which uses either the cell tower signals or Wi-Fi hotspots, to locate you within about a mile or so, at best. It doesn't have true GPS like some other mobiles on the market.

I'm not sure what law you're talking about; certainly in the EU, there is no such law that I know of.

For the current locate me function to work, the iPhone doesn't necessarily need 3 towers, as I understand it, as it is not a triangulation process that's used, despite what some people have said; one or two towers might well be enough.

As for the future, I guess that a new model of the iPhone might have true GPS on it, but no one really knows; clearly the technology is available to put GPS on small mobile devices.

Hope this answers your questions.

Message was edited by: jia10

Ronniebel,

The law requires that the cell carrier be able to provide an approximate location for the phone, and that can be done based on what towers the phone can connect to. When a phone includes GPS that is much more accurate.

The iPhone provides a location service, and a location API that can be accessed by programmers via the SDK, that is based on cell tower location, and a WiFi locator service.

One thing often overlooked with cell reception is you have to have a connection with two towers to be within a "cell".

Hope this helps,

Nathan C.

The iPhone does not have a true GPS system. The GPS used by Enhanced 911 only activates when someone actually dials 911. I assume that this is a proprietary type system and isn't designed to function as a regular user controlled GPS.

Google Locate does a reasonable job of location. Maybe with the SDK, somewhat will write a bluetooth driver that will enable people to use 3rd gps dongles in conjunction with Google Maps.

In the US, there is a federal mandate that requires newer cell phones to have a locate feature in the event that someone calls 911 from that cell phone. It will give emergency personnel a rough location of the caller if they don't know their location.

Tamara,

Enhanced 911 system works on the same concept as the Google system, just the carrier may have more accurate information on where a specific cell covers, and from their own testing in the area, how terrain in the area affects signal.

Hope this helps,

Nathan C.

I've read that but I've also read that some phones actually transmit a signal to a satellite when 911 is called.

My friend told me that by law every cell phone needs GPS for emergency location ability.

No. Not yet anyway.

In the United States, we have what's called Enhanced 911 (E911). It requires that carriers be able to determine the location of most callers to 911, within certain specs (ranging from one to a couple of football fields in distance, but soon to get smaller).

There are about a dozen ways of doing this, but they're broken into two main categories (which can be combined): GPS and tower-based. Some carriers, such as Verizon and Sprint, use GPS chips on the phone that tell the towers where they are, which is why they're able to also sell turn-by-turn navigation services on their phones.

Others, such as AT&T, use tower-based locating, where the receiving towers calculate the transmitting phone's position via timing of signal arrival, etc. I believe that AT&T uses the U-TDOA method:

[Uplink Time Difference of Arrival |http://www.trueposition.com/tech_U-TDOA.php]

Recently the FCC has gone after the carriers to make their locations more accurate for more people. Too many users can still only be located within miles (using Google map locator on the iPhone gives you a hint of that, especially if you live in the boondocks). Many observers think this means that all carriers will have to go to GPS assisted methods.

Although with the upcoming SDK it may be allowed to plug an external GPS into your bottom port of your iPhone and this would not have to be a big device. To me this would work as for most people GPS usage is not a thing used 24/7 but more for travel and giving certain situations

I've read that but I've also read that some phones actually transmit a signal to a satellite when 911 is called.

Never heard of such a cellphone, at least not a civilian one that you get from a carrier.

You might be thinking of emergency locator beacons that are picked up by satellites. These are used by airplanes, boats and even hikers these days.

iPhone's attempt at GPS is weak. For such a big brand with the newest and hottest phone, it sure is being worked over by BlackBerry's real time GPS, including in the phone. I'm really surprised iPhone isn't on this. I tried using the so-called "GPS," if you don't pick up a WiFi signal, it's simply Google Maps...and useless.

Go ahead and argue about the cons of it, I see it as lip service on Apple's behalf.

Although with the upcoming SDK it may be allowed to plug an external GPS into your bottom port

Alas, no.

[No SDK access to connector|http://blog.wired.com/gadgets/2008/03/dock-still-dark.html]

However, I think someone showed off a WiFi-based GPS puck with server, and an app on the iPhone that gets data from it that way.

SlowMow wrote:
iPhone's attempt at GPS is weak.

They never said it was an attempt at GPS. Its a simple, cell tower based location system. I have never heard a single rep for Apple claim it was as good as true GPS.

I tried using the so-called "GPS," if you don't pick up a WiFi signal, it's simply Google Maps...and useless.

This is untrue. If you are not on a WiFi network it will use cell towers and signal strength to determine your position. It works fairly well if you are in a larger urban area - for me it pings within a block or two.

And did the first generation Blackberry have GPS? You're comparing a first generation product (iPhone) against a well established cell phone product.

A lot of people seem to lose sight of the fact that the iPhone is a first generation product. It hasn't gone through 5 or 10 product cycles over the last 5 years.

<Edited by Moderator> No, BlackBerry first generation didn't have GPS...and I never said first generation...all I said was, Apple is attempting GPS, it's not working. Just like PB&J in the same jar, doesn't work. All hype, little excitement, I'm learning.

Don't attack my opinion, I'm sensitive.

..the iPhone is a first generation product

So what? Not an excuse. Unless you think Apple engineers are stupid, and I assume you don't. A newbie engineer could easily design a new phone using off-the-shelf components, with 3G and GPS. It's not rocket science.

I'd bet that many first-generation Android phones will have such features.

Apple had the advantage of building on a decade or two of other's R&D. This gave Apple access to portable cpus, radio chips, displays, touchscreens, etc that would not have otherwise been affordable.

No, things such as GPS and 3G are left out because of deliberate cost calculations, not because it's a "first generation" device per se.